The school distributions by age is given for 215 delinquents in the California State School at Whittier for boys by Williams ([62]) in sufficient detail to make it usable for estimating the frequency of deficiency on a plan we shall consider shortly. Regarding age seven as satisfactory for the first grade, and so on, only 7 of these boys had reached this standard. Supposing that those older should have attained at least the grade which is satisfactory for the 14-year-old, and those younger the corresponding grades, we find that 29% were four or more years below this standard and 14% were five years below this standard. In the next section we shall endeavor to find out how the school records might also be used as symptomatic of mental capacity.
[31]. The tables of Minneapolis school children were prepared by Mr. Andrew J. Lein and of delinquents by Miss Lydia B. Christ, to whom I am much indebted.
CHAPTER IX. COMPARISON OF THE SCHOOL TEST AND THE BINET TEST
There has been considerable discussion of the question whether psychological testing should be expected to conform to the ranking of pupils in school. This discussion however, does not attack the question in which we are especially interested, i. e., how to get the best information from both. If the school level were measured by the progress made in school by passable work and not by the school position attained often merely through age or size, Binet would be right in expecting that in general they would correspond among groups of children in the public schools. Agreement with real school progress could, therefore, be taken as a criterion of a good series of tests, as it has been by Binet and Bobertag. On the other hand Meumann and Abelson were right in objecting to the proof of the value of tests by agreement with the school level, if they limited their objection to tests applied to exceptional children and to using school position as a final test of school level. Lack of correspondence with our group of delinquents is, of course, no indication of a weakness in the Binet scale. In numerous instances they had been promoted in school because of age without doing passable work. The reader should also see the evidence of the teacher's bad judgment of a pupil's ability assembled by Terman and by Terman and Knollen ([196]).
Terman has calculated the correlation between intelligence quotients determined by the Binet scale and the teacher's estimates of scholastic or of general ability. These gave coefficients of .48 and .45. Doll has found for Goddard's data on school children that the correlation of school grades is closer with life-age than with test-age, .84 as compared with .73 ([12]). This indicates an influence of life-age upon promotion. In a school for deficients Burt found the correlation of teachers' estimates with Binet ages was .55, with mental retardation or excess .59, with intellectual quotient .48. He quotes McIntyre and Rogers as finding coefficients about .5 for similar calculations with normal school children in Scotland ([85]). Starch has shown that measured by the combined ability in reading, writing and spelling a third of the pupils are in a grade behind and a third are in a grade ahead of their ability ([186]).
However much we might disagree as to how close a correlation might be expected between the Binet tests and school level, independent of the relation to life-ages, or which is the better test, it is certain that they afford two different symptoms of mental deficiency. It becomes our immediate problem, therefore, to discover how the most information may be gained from a careful interpretation of the test of school level. If we had sufficient data, three sorts of checks might be formulated. 1. What amount of school retardation will give us the best estimate of mental deficiency among groups? 2. What amount of school retardation should put an individual's mentality in question so that he should be examined? 3. What amount of school success should put in question a Binet diagnosis?
A. Practical Uses of the School Test.
(a) Estimating the Frequency of Deficiency By School Retardation.
We shall first take up the question of utilizing information about school retardation in estimating the frequency of mental deficiency among groups of delinquents. It is perfectly clear that retardation in school position is not always an indication of mental retardation. A child may be behind the position in school reached by the children of his age merely because he has not attended school so long as his companions. A census of school progress which we took in Minnesota indicates that in general a large part, perhaps half, of the retardation in school is to be thus explained even under compulsory attendance laws. Some allowance is also to be made for physical handicaps, such as defects of sight and hearing which are not corrected, illness which does not cause prolonged absence, frequent change of schools, bad home conditions, etc. Aside from absence, however, there can be no question that greater or less degrees of mental retardation is the main cause of retardation in school. Moreover a dull mind is often the reason for beginning school at an older age and for staying away from an unsuitable school environment as much as the law will permit. In any particular case, it is to be noted, however, that all of the excuses for backwardness in school are not likely to account for more than one or two years of lagging for other reasons than dullness.